Front end module with a tunable balancing network

ABSTRACT

A radio front module includes a power amplifier, a duplexer, and a tunable balancing network. The power amplifier is operably coupled to amplify an up-converted signal into an outbound wireless signal. The duplexer is operably coupled to an antenna and operable to provide electrical isolation between the outbound wireless signal and an inbound wireless signal. The tunable balancing network is operable to establish an impedance that substantially matches an impedance of the antenna. The tunable balancing network includes a plurality of capacitive elements, a plurality of resistive elements, and a plurality of low-voltage switching elements operable to, and in accordance with a tuning signal, couple one or more of the plurality of capacitive elements and one or more of the plurality of resistive elements to the duplexer as an impedance balancing load.

CROSS REFERENCE TO RELATED PATENTS

This patent application is claiming priority under 35 USC §119(e) to aprovisionally filed patent application entitled CONFIGURABLE ANDSCALABLE RF FRONT-END MODULE, having a provisional filing date of Jun.3, 2010, and a provisional Ser. No. 61/351,284, which is incorporated byreference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

NOT APPLICABLE

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

NOT APPLICABLE

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to wireless communications and moreparticularly to radio transceivers.

2. Description of Related Art

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), radio frequencyidentification (RFID), Enhanced Data rates for GSM Evolution (EDGE),General Packet Radio Service (GPRS), WCDMA, LTE (Long Term Evolution),WiMAX (worldwide interoperability for microwave access), and/orvariations thereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, RFID reader, RFID tag, et ceteracommunicates directly or indirectly with other wireless communicationdevices. For direct communications (also known as point-to-pointcommunications), the participating wireless communication devices tunetheir receivers and transmitters to the same channel or channels (e.g.,one of the plurality of radio frequency (RF) carriers of the wirelesscommunication system or a particular RF frequency for some systems) andcommunicate over that channel(s). For indirect wireless communications,each wireless communication device communicates directly with anassociated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe Internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the receiver is coupled to anantenna and includes a low noise amplifier, one or more intermediatefrequency stages, a filtering stage, and a data recovery stage. The lownoise amplifier receives inbound RF signals via the antenna andamplifies then. The one or more intermediate frequency stages mix theamplified RF signals with one or more local oscillations to convert theamplified RF signal into baseband signals or intermediate frequency (IF)signals. The filtering stage filters the baseband signals or the IFsignals to attenuate unwanted out of band signals to produce filteredsignals. The data recovery stage recovers data from the filtered signalsin accordance with the particular wireless communication standard.

As is also known, the transmitter includes a data modulation stage, oneor more intermediate frequency stages, and a power amplifier. The datamodulation stage converts data into baseband signals in accordance witha particular wireless communication standard. The one or moreintermediate frequency stages mix the baseband signals with one or morelocal oscillations to produce RF signals. The power amplifier amplifiesthe RF signals prior to transmission via an antenna.

To implement a radio transceiver, a wireless communication deviceincludes a plurality of integrated circuits (ICs) and a plurality ofdiscrete components. FIG. 1 illustrates an example of a wirelesscommunication device that supports 2G and 3G cellular telephoneprotocols. As shown, the wireless communication device includes abaseband processing IC, a power management IC, a radio transceiver IC, atransmit/receive (T/R) switch, an antenna, and a plurality of discretecomponents. The discrete components include surface acoustic wave (SAW)filters, power amplifiers, duplexers, inductors, and capacitors. Suchdiscrete components add several dollars (US) to the bill of material forthe wireless communication device, but are necessary to achieve thestrict performance requirements of the 2G and 3G protocols.

As integrated circuit fabrication technology evolves, wirelesscommunication device manufacturers require that wireless transceiver ICmanufacturers update their ICs in accordance with the advancements in ICfabrication. For example, as the fabrication process changes (e.g., usessmaller transistor sizes), the wireless transceiver ICs are redesignedfor the newer fabrication process. Redesigning the digital portions ofthe ICs is a relatively straightforward process since most digitalcircuitry “shrinks” with the IC fabrication process. Redesigning theanalog portions, however, is not a straightforward task since mostanalog circuitry (e.g., inductors, capacitors, etc.) does not “shrink”with the IC process. As such, wireless transceiver IC manufacturersinvest significant effort to produce ICs of newer IC fabricationprocesses.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theDrawings, the Detailed Description of the Invention, and the claims.Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of a prior art wirelesscommunication device;

FIG. 2 is a schematic block diagram of an embodiment of a portablecomputing communication device in accordance with the present invention;

FIG. 3 is a schematic block diagram of another embodiment of a portablecomputing communication device in accordance with the present invention;

FIG. 4 is a schematic block diagram of another embodiment of a portablecomputing communication device in accordance with the present invention;

FIG. 5 is a schematic block diagram of another embodiment of a portablecomputing communication device in accordance with the present invention;

FIG. 6 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 7 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 8 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an LNA in accordance with thepresent invention;

FIG. 9 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 10 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 11 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 12 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 13 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 14 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 15 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 16 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) and an SOC module in 2G TX mode inaccordance with the present invention;

FIG. 17 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) and an SOC module in 2G RX mode inaccordance with the present invention;

FIG. 18 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 19 is a schematic block diagram of an embodiment of a small signalbalancing network in accordance with the present invention;

FIG. 20 is a schematic block diagram of an embodiment of a large signalbalancing network in accordance with the present invention;

FIG. 21 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an LNA in accordance with thepresent invention;

FIG. 22 is a schematic block diagram of an embodiment of an impedance inaccordance with the present invention;

FIG. 23 is a schematic block diagram of another embodiment of animpedance in accordance with the present invention;

FIG. 24 is a schematic block diagram of an embodiment of a balancingnetwork in accordance with the present invention;

FIG. 25 is a schematic block diagram of another embodiment of abalancing network in accordance with the present invention;

FIG. 26 is a schematic block diagram of an embodiment of a clockgenerator for clocking a balancing network in accordance with thepresent invention;

FIG. 27 is a diagram of an operational example of the balancing networkof FIG. 25 in accordance with the present invention;

FIG. 28 is a schematic block diagram of another embodiment of abalancing network in accordance with the present invention;

FIG. 29 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) in accordance with the presentinvention;

FIG. 30 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 31 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention;

FIG. 32 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an LNA in accordance with thepresent invention;

FIG. 33 is a schematic block diagram of an embodiment of an equivalentcircuit of a portion of each of a front-end module (FEM) and an LNA inaccordance with the present invention;

FIG. 34 is a schematic block diagram of an embodiment of a transformerbalun in accordance with the present invention;

FIG. 35 is a diagram of an example of an implementation of a transformerbalun in accordance with the present invention;

FIG. 36 is a diagram of another example of an implementation of atransformer balun in accordance with the present invention;

FIG. 37 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention; and

FIG. 38 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) and an SOC module in accordance withthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 is a schematic block diagram of an embodiment of a portablecomputing communication device 10 that includes a system on a chip (SOC)12 and a front-end module (FEM) 14. The portable computing communicationdevice 10 may be any device that can be carried by a person, can be atleast partially powered by a battery, includes a radio transceiver(e.g., radio frequency (RF) and/or millimeter wave (MMW)) and performsone or more software applications. For example, the portable computingcommunication device 10 may be a cellular telephone, a laptop computer,a personal digital assistant, a video game console, a video game player,a personal entertainment unit, a tablet computer, etc.

The SOC 12 includes a SAW-less receiver section 18, a SAW-lesstransmitter section 20, a baseband processing unit 22, a processingmodule 24, and a power management unit 26. The SAW-less receiver 18includes a receiver (RX) radio frequency (RF) to intermediate frequency(IF) section 28 and a receiver (RX) IF to baseband (BB) section 30. TheRX RF to IF section 28 further includes one or more frequency translatedbandpass filters (FTBPF) 32.

The processing module 24 and the baseband processing unit 22 may be asingle processing device, separate processing devices, or a plurality ofprocessing devices. Such a processing device may be a microprocessor,micro-controller, digital signal processor, microcomputer, centralprocessing unit, field programmable gate array, programmable logicdevice, state machine, logic circuitry, analog circuitry, digitalcircuitry, and/or any device that manipulates signals (analog and/ordigital) based on hard coding of the circuitry and/or operationalinstructions. The processing module 24 and/or baseband processing unit22 may have an associated memory and/or memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of the processing module 24. Such a memory device may be aread-only memory, random access memory, volatile memory, non-volatilememory, static memory, dynamic memory, flash memory, cache memory,and/or any device that stores digital information. Note that if theprocessing module 24 and/or baseband processing unit 22 includes morethan one processing device, the processing devices may be centrallylocated (e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that when the processing module 24 and/or basebandprocessing unit 22 implements one or more of its functions via a statemachine, analog circuitry, digital circuitry, and/or logic circuitry,the memory and/or memory element storing the corresponding operationalinstructions may be embedded within, or external to, the circuitrycomprising the state machine, analog circuitry, digital circuitry,and/or logic circuitry. Still further note that, the memory elementstores, and the processing module 24 and/or baseband processing unit 22executes, hard coded and/or operational instructions corresponding to atleast some of the steps and/or functions illustrated in one or more ofthe Figures.

The front-end module (FEM) 14 includes one or more of a plurality ofpower amplifiers (PA) 34-36, a plurality of receiver-transmitter (RX-TX)isolation modules 38-40, a plurality of antenna tuning units (ATU)42-44, and a frequency band (FB) switch 46. Note that the FEM 14 mayinclude more than two paths of PAs 34-36, RX-TX isolation modules 38-40,and ATUs 42-44 coupled to the FB switch 46. For example, the FEM 14 mayinclude one path for 2G (second generation) cellular telephone service,another path for 3G (third generation) cellular telephone service, and athird path for wireless local area network (WLAN) service. Of coursethere a multitude of other example combinations of paths within the FEM14 to support one or more wireless communication standards (e.g., IEEE802.11, Bluetooth, global system for mobile communications (GSM), codedivision multiple access (CDMA), radio frequency identification (RFID),Enhanced Data rates for GSM Evolution (EDGE), General Packet RadioService (GPRS), WCDMA, high-speed downlink packet access (HSDPA),high-speed uplink packet access (HSUPA), LTE (Long Term Evolution),WiMAX (worldwide interoperability for microwave access), and/orvariations thereof).

In an example of operation, the processing module 24 is performing oneor more functions that require wireless transmission of data. In thisinstance, the processing module 24 provides the outbound data (e.g.,voice, text, audio, video, graphics, etc.) to the baseband processingmodule 22, which converts the outbound data into one or more outboundsymbol streams in accordance with one or more wireless communicationstandards (e.g., GSM, CDMA, WCDMA, HSUPA, HSDPA, WiMAX, EDGE, GPRS, IEEE802.11, Bluetooth, ZigBee, universal mobile telecommunications system(UMTS), long term evolution (LTE), IEEE 802.16, evolution data optimized(EV-DO), etc.). Such a conversion includes one or more of: scrambling,puncturing, encoding, interleaving, constellation mapping, modulation,frequency spreading, frequency hopping, beamforming, space-time-blockencoding, space-frequency-block encoding, frequency to time domainconversion, and/or digital baseband to intermediate frequencyconversion. Note that the processing module 24 converts the outbounddata into a single outbound symbol stream for Single Input Single Output(SISO) communications and/or for Multiple Input Single Output (MISO)communications and converts the outbound data into multiple outboundsymbol streams for Single Input Multiple Output (SIMO) and MultipleInput Multiple Output (MIMO) communications.

The baseband processing unit 22 provides the one or more outbound symbolstreams to the SAW-less transmitter section 20, which converts theoutbound symbol stream(s) into one or more outbound RF or MMW signals.The SAW-less transceiver section 20 may include a direct conversiontopology (e.g., direct conversion of baseband or near baseband symbolstreams to RF signals) or a super heterodyne topology (e.g., convertbaseband or near baseband symbol streams into IF signals and thenconvert the IF signals into RF signals).

For a direction conversion, the SAW-less transmitter section 20 may havea Cartesian-based topology, a polar-based topology, or a hybridpolar-Cartesian-based topology. In a Cartesian-based topology, theSAW-less transmitter section 20 mixes in-phase and quadrature components(e.g., A_(I)(t)cos(ω_(BB)(t)+Φ_(I)(t)) andA_(Q)(t)cos(ω_(BB)(t)+φ_(Q)(t)), respectively) of the one or moreoutbound symbol streams with in-phase and quadrature components (e.g.,cos(ω_(RF)(t)) and sin(ω_(RF)(t)), respectively) of one or more transmitlocal oscillations (TX LO) to produce mixed signals. The mixed signalsare combined and filtered to produce one or more outbound up-convertedsignals (e.g., A(t)cos(ω_(BB)(t)+φ(t))+ω_(RF)(t))). A power amplifierdriver (PAD) module amplifies the outbound up-converted signal(s) toproduce a pre-PA (power amplified) outbound RF signal(s).

In a phase polar-based topology, the SAW-less transmitter section 20includes an oscillator that produces an oscillation (e.g.,cos(ω_(RF)(t)) this is adjusted based on the phase information (e.g.,+/−Δφ [phase shift] and/or φt) [phase modulation]) of the outboundsymbol stream(s). The resulting adjusted oscillation (e.g.,cos(ω_(RF)(t)+/−Δφ) or cos(ω_(RF)(t)+φ(t)) may be further adjusted byamplitude information (e.g., A(t) [amplitude modulation]) of theoutbound symbol stream(s) to produce one or more up-converted signals(e.g., A(t)cos(ω_(RF)(t)+φ(t)) or A(t)cos(ω_(RF)(t)+/−Δφ)). A poweramplifier driver (PAD) module amplifies the outbound up-convertedsignal(s) to produce a pre-PA (power amplified) outbound RF signal(s).

In a frequency polar-based topology, the SAW-less transmitter section 20includes an oscillator that produces an oscillation (e.g.,cos(ω_(RF)(t)) this is adjusted based on the frequency information(e.g., +/−Δf [frequency shift] and/or f(t)) [frequency modulation]) ofthe outbound symbol stream(s). The resulting adjusted oscillation (e.g.,cos(ω_(RF)(t)+/−Δf) or cos(ω_(RF)(t)+f(t)) may be further adjusted byamplitude information (e.g., A(t) [amplitude modulation]) of theoutbound symbol stream(s) to produce one or more up-converted signals(e.g., A(t)cos(ω_(RF)(t)+f(t)) or A(t)cos(ω_(RF)(t)+/−Δf)). A poweramplifier driver (PAD) module amplifies the outbound up-convertedsignal(s) to produce a pre-PA (power amplified) outbound RF signal(s).

In a hybrid polar-Cartesian-based topology, the SAW-less transmittersection 20 separates the phase information (e.g., cos(ω_(BB)(t)+/−Δφ) orcos(ω_(BB)(t)+φ(t)) and the amplitude information (e.g., A(t)) of theoutbound symbol stream(s). The SAW-less transmitter section 20 mixesin-phase and quadrature components (e.g., cos(ω_(BB)(t)+φ_(I)(t)) andcos(ω_(BB)(t)+φ_(Q)(t)), respectively) of the one or more outboundsymbol streams with in-phase and quadrature components (e.g.,cos(ω_(RF)(t)) and sin(ω_(RF)(t)), respectively) of one or more transmitlocal oscillations (TX LO) to produce mixed signals. The mixed signalsare combined and filtered to produce one or more normalized outboundup-converted signals (e.g., cos(ω_(BB)(t)+φ(t))+ω_(RF)(t))). A poweramplifier driver (PAD) module amplifies the normalized outboundup-converted signal(s) and injects the amplitude information (e.g.,A(t)) into the normalized outbound up-converted signal(s) to/produce apre-PA (power amplified) outbound RF signal(s) (e.g., A(t)cos(ω_(RF)(t)+φ(t)).

For a super heterodyne topology, the SAW-less transmitter section 20includes a baseband (BB) to intermediate frequency (IF) section and anIF to a radio frequency (RF section). The BB to IF section may be of apolar-based topology, a Cartesian-based topology, a hybridpolar-Cartesian-based topology, or a mixing stage to up-convert theoutbound symbol stream(s). In the three former cases, the BB to IFsection generates an IF signal(s) (e.g., A(t)cos(ω_(IF)(t)+φ(t))) andthe IF to RF section includes a mixing stage, a filtering stage and thepower amplifier driver (PAD) to produce the pre-PA outbound RFsignal(s).

When the BB to IF section includes a mixing stage, the IF to RF sectionmay have a polar-based topology, a Cartesian-based topology, or a hybridpolar-Cartesian-based topology. In this instance, the BB to IF sectionconverts the outbound symbol stream(s) (e.g., A(t)cos((ω_(BB)(t)+φ(t)))into intermediate frequency symbol stream(s) (e.g., A(t)(ω_(IF)(t)+φ(t)). The IF to RF section converts the IF symbol stream(s)into the pre-PA outbound RF signal(s).

The SAW-less transmitter section 20 outputs the pre-PA outbound RFsignal(s) to a power amplifier module (PA) 34-36 of the front-end module(FEM) 14. The PA 34-36 includes one or more power amplifiers coupled inseries and/or in parallel to amplified the pre-PA outbound RF signal(s)to produce an outbound RF signal(s). Note that parameters (e.g., gain,linearity, bandwidth, efficiency, noise, output dynamic range, slewrate, rise rate, settling time, overshoot, stability factor, etc.) ofthe PA 34-36 may be adjusted based on control signals received from thebaseband processing unit 22 and/or the processing module 24. Forinstance, as transmission conditions change (e.g., channel responsechanges, distance between TX unit and RX unit changes, antennaproperties change, etc.), the processing resources (e.g., the BBprocessing unit 22 and/or the processing module 24) of the SOC 12monitors the transmission condition changes and adjusts the propertiesof the PA 34-36 to optimize performance. Such a determination typicallyis not made in isolation; it is done in light to other parameters of thefront-end module that may be adjusted (e.g., the ATU 42-44, the RX-TXisolation module 38-40) to optimize transmission and reception of the RFsignals.

The RX-TX isolation module 38-40 (which may include a balancing networkand a duplexer, a circulator, a transformer balun, or other device thatprovides isolation between a TX signal and an RX signal using a commonantenna) attenuates the outbound RF signal(s). The RX-TX isolationmodule 38-40 may adjusts it attenuation of the outbound RF signal(s)(i.e., the TX signal) based on control signals received from thebaseband processing unit and/or the processing module 24 of the SOC 12.For example, when the transmission power is relatively low, the RX-TXisolation module 38-40 may be adjusted to reduce its attenuation of theTX signal.

The antenna tuning unit (ATU) 42-44, if included, is tuned to provide adesired impedance that substantially matches that of the antenna 16. Astuned, the ATU 42-44 provides the attenuated TX signal from the RX-TXisolation module 38-40 to the antenna 16 for transmission. Note that theATU 42-44 may be continually or periodically adjusted to track impedancechanges of the antenna 16. For example, the baseband processing unit 22and/or the processing module 24 may detect a change in the impedance ofthe antenna 16 and, based on the detected change, provide controlsignals to the ATU 42-44 such that it changes it impedance accordingly.

In this example, the SAW-less transmitter 20 section has two outputs:one for a first frequency band and the other for a second frequencyband. The preceding discussion has focused on the process of convertingoutbound data into outbound RF signals for a single frequency band(e.g., 850 MHz, 900 MHz, etc.). The process is similar for convertingoutbound data into RF signals for the other frequency band (e.g., 1800MHz, 1900 MHz, 2100 MHz, 2.4 GHz, 5 GHz, etc.). Note that with a singleantenna 16, the SAW-less transmitter 20 generates outbound RF signals inone of the other frequency bands. The frequency band (FB) switch 46 ofthe FEM 14 couples the antenna 16 to the appropriate output of theSAW-less transmitter output path. The FB switch 46 receives controlinformation from the baseband processing unit 22 and/or the processingmodule 24 to select which path to connect to the antenna 16.

The antenna 16 also receives one or more inbound RF signals, which areprovided to one of the ATUs 42-44 via the frequency band (FB) switch 46.The ATU 42-44 provides the inbound RF signal(s) to the RX-TX isolationmodule 38-40, which routes the signal(s) to the receiver (RX) RF to IFsection 28 of the SOC 12. The RX RF to IF section 28 converts theinbound RF signal(s) (e.g., A(t)cos(ω_(RF)(t)+φ(t))) into an inbound IFsignal (e.g., A_(I)(t)cos(ω_(IF)(t)+φ_(I)(t)) andA_(Q)(t)cos(ω_(IF)(t)+φ_(Q)(t))). Various embodiments of the RX RF to IFsection 28 will be described in several of the subsequent figures.

The RX IF to BB section 30 converts the inbound IF signal into one ormore inbound symbol streams (e.g., A(t)cos((ω_(BB)(t)+φ(t))). In thisinstance, the RX IF to BB section 30 includes a mixing section and acombining & filtering section. The mixing section mixes the inbound IFsignal(s) with a second local oscillation (e.g., LO2=IF−BB, where BB mayrange from 0 Hz to a few MHz) to produce I and Q mixed signals. Thecombining & filtering section combines (e.g., adds the mixed signalstogether—which includes a sum component and a difference component) andthen filters the combined signal to substantially attenuate the sumcomponent and pass, substantially unattenuated, the difference componentas the inbound symbol stream(s).

The baseband processing unit 22 converts the inbound symbol stream(s)into inbound data (e.g., voice, text, audio, video, graphics, etc.) inaccordance with one or more wireless communication standards (e.g., GSM,CDMA, WCDMA, HSUPA, HSDPA, WiMAX, EDGE, GPRS, IEEE 802.11, Bluetooth,ZigBee, universal mobile telecommunications system (UMTS), long termevolution (LTE), IEEE 802.16, evolution data optimized (EV-DO), etc.).Such a conversion may include one or more of: digital intermediatefrequency to baseband conversion, time to frequency domain conversion,space-time-block decoding, space-frequency-block decoding, demodulation,frequency spread decoding, frequency hopping decoding, beamformingdecoding, constellation demapping, deinterleaving, decoding,depuncturing, and/or descrambling. Note that the processing module 24converts a single inbound symbol stream into the inbound data for SingleInput Single Output (SISO) communications and/or for Multiple InputSingle Output (MISO) communications and converts the multiple inboundsymbol streams into the inbound data for Single Input Multiple Output(SIMO) and Multiple Input Multiple Output (MIMO) communications.

The power management unit 26 is integrated into the SOC 12 to perform avariety of functions. Such functions include monitoring powerconnections and battery charges, charging a battery when necessary,controlling power to the other components of the SOC 12, generatingsupply voltages, shutting down unnecessary SOC modules, controllingsleep modes of the SOC modules, and/or providing a real-time clock. Tofacilitate the generation of power supply voltages, the power managementunit 26 may includes one or more switch-mode power supplies and/or oneor more linear regulators.

With such an implementation of a portable computing communication device10, expensive and discrete off-chip components (e.g., SAW filters,duplexers, inductors, and/or capacitors) are eliminated and theirfunctionality is incorporated in the front-end module (FEM) 14 that canbe implemented on a single die. Further, the SAW-less receiverarchitecture and the SAW-less transmitter architecture facilitate theelimination of the discrete off-chip components.

FIG. 3 is a schematic block diagram of another embodiment of a portablecomputing communication device 10 that includes a system on a chip (SOC)52 and another embodiment of a front-end module (FEM) 50. The SOC 52includes the power management unit 26, the SAW-less receiver section 18,the SAW-less transmitter section 20, the baseband processing unit 22,and may further include the processing module. The FEM 50 includes aplurality of power amplifier modules (PA) 34-36, a plurality of RX-TXisolation modules 38-40, and at least one antenna tuning unit (ATU) 54.

In this embodiment, the SOC 52 is operable to concurrently support twoor more wireless communications (e.g., a cellular telephone call and aWLAN communication and/or a Bluetooth communication). In this instance,the SAW-less transmitter 20 generates two (or more) different frequencyband outbound RF signals in a manner discussed with reference to FIG. 2and/or with reference to one or more subsequent figures. A first one ofthe different frequency outbound RF signals is provided to one of thePAs 34-36 of the FEM 50 and the other outbound RF signal is provided tothe other PA 34-36. Each of the TX-RX isolation modules 38-40 functionsas described with reference to FIG. 2 and as may be described withreference to one or more of the subsequent figures. The ATU 54, which istuned based on control signals from the SOC 52, provides the twooutbound RF signals to the antenna 16 for transmission.

The antenna 16 also receives two or more different frequency bandinbound RF signals, which it provides to the ATU 54. The ATU 54 mayincludes a splitter to separate the two inbound RF signals and separateimpedance matching circuits (e.g., one or more LC circuits) for eachseparated signal; a transformer balun to separate the signals andseparate impedance matching circuits; or an impedance matching circuitsfor the two signals, which are provided to the RX-TX isolation modules38-40.

The RX-TX isolation modules 38-40 are each frequency band dependent suchthat each will only pass inbound and outbound RF signals within theirrespective frequency bands (e.g., 850-900 MHz and 1800-1900 MHz). Assuch, a first TX-RX isolation module 38-40 provides a first frequencyband inbound RF signal to a first input of the SAW-less RX section 18and the second TX-RX isolation module 38-40 provides the secondfrequency band inbound RF signal to a second input of the SAW-less RXsection 18. The SAW-less RX section 18 processes the inbound RF signalsto produce first inbound data and second inbound data in manner asdiscussed with reference to FIG. 2 and/or as will be discussed withreference to one or more of the subsequent figures.

FIG. 4 is a schematic block diagram of another embodiment of a portablecomputing communication device that includes a system on a chip (SOC)180 coupled to a front-end module (FEM) 182. The SOC 180 includes aplurality of SAW-less receiver sections (only the LNA and frequencytranslated bandpass filter (FTBPF) of the receiver section are shown), aplurality of SAW-less transmitter sections (only the power amplifierdriver (PAD) are shown), the processing module, the baseband processingmodule (not shown or included in the processing module), and the powermanagement unit (not shown).

The FEM 182 includes a low frequency band (LB) path, a high frequencyband (HB) path, and a frequency band switch (FB SW). The LB pathincludes a power amplifier module (PA), a low band impedance stage (LBZ), a low band low pass filter (LB LPF), a switch (SW), atransmit-receive isolation module (TX-RX ISO) (e.g., a duplexer), asecond switch (SW), and an antenna tuning unit (ATU). The HB pathincludes a power amplifier module (PA), a high band impedance stage (HBZ), a high band low pass filter (HB LPF), a switch (SW), atransmit-receive isolation module (TX-RX ISO) (e.g., a duplexer), asecond switch (SW), and an antenna tuning unit (ATU). Note that the lowband path may be used to support low band GSM, EDGE, and/or WCDMAwireless communications and the high band path may be used to supporthigh band GSM, EDGE, and/or WCDMA wireless communications.

The SOC 180 functions to output pre-PA outbound RF signals and to inputinbound RF signals as previously discussed and/or as will be discussedwith reference to one or more of the subsequent figures. The FEM 182receives the pre-PA outbound RF signals via the LB path or the HB pathand amplifies them via the corresponding PA module. The impedance stage(LB Z or HB Z) provides a desired load on the output of the PA modulesand is coupled to the low pass filter (LB LPF or HP LPF). The LPFfilters the outbound RF signal, which is provided to the TX-RX ISOmodule or to the ATU depending on the configuration of the switches(SW). If switches couple the LPF to the TX-RX ISO module, the TX-RXmodule attenuates the outbound RF signals before providing them to theATU. The ATU functions as previously described and/or as will bedescribed with reference to one or more of the subsequent figures.

Note that there are no discrete components between the SOC 180 and theFEM 182. In particular, the portable computing communication device doesnot need discrete SAW-filters as are required in current cellulartelephone implementations. One or more of the architecture of theSAW-less receiver, the architecture of the SAW-less transmitter, and/orthe programmability of the various components of the FEM 182 contributeto the elimination of SAW filters and/or other conventional externaldiscrete components.

FIG. 5 is a schematic block diagram of another embodiment of a portablecomputing communication device that includes a system on a chip (SOC)190 coupled to a front-end module (FEM) 192. The SOC 190 includes aplurality of SAW-less receiver sections (only the LNA and frequencytranslated bandpass filter (FTBPF) of the receiver section is shown), aplurality of SAW-less transmitter sections (only the power amplifierdriver (PAD) is shown), the processing module, the baseband processingmodule (not shown or included in the processing module), and the powermanagement unit (not shown).

The FEM 192 includes a low frequency band (LB) path, a high frequencyband (HB) path, and a frequency band switch (FB SW). The LB pathincludes a power amplifier module (PA), a low band impedance stage (LBZ), a switch (SW), a low band low pass filter (LB LPF), atransmit-receive isolation module (TX-RX ISO) (e.g., a duplexer), asecond switch (SW), and an antenna tuning unit (ATU). The HB pathincludes a power amplifier module (PA), a high band impedance stage (HBZ), a switch (SW), a high band low pass filter (HB LPF), atransmit-receive isolation module (TX-RX ISO) (e.g., a duplexer), asecond switch (SW), and an antenna tuning unit (ATU). Note that the lowband path may be used to support low band GSM, EDGE, and/or WCDMAwireless communications and the high band path may be used to supporthigh band GSM, EDGE, and/or WCDMA wireless communications.

In the various embodiments of the SOC 190, the frequency translatedbandpass filter in the receiver section of the SOC 190 sufficientlyfilters the far-out blockers and filters the image signal withnegligible affect on the desired signal. This reduces the dynamic rangerequirement of the analog to digital converters (ADC) of the receiversection (at the output end of the baseband processing module or at theinput of the RX BB to IF section). The super heterodyne architecture ofthe receiver section is optimal for reducing power consumption and diearea in comparison to a comparable direction conversion receiversection.

FIG. 6 is a schematic block diagram of a front end module 810 and asystem-on-a-chip module 812. The front end module 810 includes aduplexer 816 and a tunable balancing network 818. The system on a chipmodule 812 includes a detector module 820 and a processing module 822.Note that, processing module 822, like any other processing modulediscussed in this application, may be constructed as described withreference to processing module 24 of FIG. 2.

In an example of operation, the duplexer is couple to an antenna 826that transceivers inbound and outbound wireless signals 835 and 837. Forexample, the inbound and outbound wireless signals 835 & 837 maycorrespond to a radio frequency (RF) signals produced in accordance withone or more wireless communication protocols of which examples have beenpreviously provided. As a more specific example, the outbound wirelesssignal 835 has a carrier frequency that corresponds to a transmitfrequency of a wireless communication protocol and the inbound wirelesssignal 835 has a carrier frequency that corresponds to a receivefrequency band of the wireless indication protocol.

The duplexer 816 provides electrical isolation between the inboundwireless signal 837 and the outbound wireless signal 835. The duplexer816 may be a frequency—selective duplexer or an electrical—balanceduplexer to provide 30 dB or more of isolation between the inbound andoutbound wireless signals 835 and 837.

The tunable balancing network 818 is operable to establish on impedancethat substantially matches on an impedance of the antenna based on atuning signal 823. In general, energy (e.g., current and/or voltage) ofthe outbound wireless signal 835 is divided into two paths. The firstpath is to the antenna 826 and the second path is to the tunablebalancing network 818. If the paths are substantially equal, then theenergy will be substantially equal, which effectively cancels out theoutbound wireless signal 835 coupling into the inbound wireless signal837 portion of duplex or 816.

To maintain the impedance balance of the tunable balancing network 818with the changing impedance of the antenna 826, the detector module 820monitors an electrical performance characteristic of the duplexer 816.For example, the detector module 820 monitors a common mode of theduplexer 816 to detect for a common mode offset due to impedanceimbalance between the antenna and tunable balancing network 818. If anoffset is detected, the detector module 820 generates an error signaled.Note that other electrical performance characteristics include, but arenot limited to, impedance mismatches within the duplexer, nonlinearityof one or more components of the duplexer, and/or frequency dependentcomponent responses.

The processing module 822, functioning as a tuning engine, generates thetuning signal 823 based on the error signal. For example, the errorsignal may indicate that the impedance of the tunable balancing network818 is less than the impedance of the antenna 826. In this instance, theprocessing module generates the tuning signal 823 to increase theimpedance of the tunable balancing network 818 to more closely match theantenna's impedance. Note that this is a dynamic process as theimpedance of the antenna changes based on environmental conditions suchas proximity to metal objects, multipath fading, etc.

FIG. 7 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) 810 and an SOC 812. The portion of theFEM 810 includes a power amplifier module (PA) 814, a duplexer 816, abalance network 818, and a sensing circuit 817. The duplexer includes atransformer (or other structure such as a frequency selective duplexerand/or an electrical balance duplexer) and the balancing network 818includes at least one of a tunable resistor-capacitor network, a tunableinductor-capacitor network, and a tunable resistor-inductor-capacitornetwork. The sensing circuit 817, to sense the electrical performancecharacteristic of the duplexer, includes a pair of resistors coupledacross the secondary winding of the transformer. The portion of the SOC812 includes a peak detector 820, a tuning engine 822, and a low noiseamplifier module (LNA). Alternatively, the peak detector 820 and/or thetuning engine 822 may be within the FEM 810.

In an example of operation, the PA 814 supplies an outbound RF signal tothe center tap of the dual winding primary of the transformer duplexer816. Current of the outbound RF signal is split between the two windingsproportional to the difference in impedance between the antenna and thebalancing network 818. If the impedance of the balancing network 818substantially matches the impedance of the antenna, the current isessentially equally split between the two windings.

With the winding configuration as shown, if the currents in the primarywindings substantially match, their magnetic fields essential canceleach other in the secondary winding. Thus, the secondary has asubstantially attenuated representation of the outbound RF signal. Foran inbound RF signal, the two windings of the primary generate amagnetic field corresponding to the current of the inbound RF signal. Inthis instance, the magnetic fields are added, thus producing twice thecurrent in the secondary than in the primary (assuming each of thewindings has the same number of turns). As such, the transformeramplifies the inbound RF signal.

If there is an imbalance between the impedance of the antenna and theimpedance of the balancing network 818, an outbound RF signal currentcomponent will be present in the secondary (e.g., TX leakage). Forexample, assume that the current through the winding to the inductor isi_(P1) and the current through the winding to the balance network 818 isi_(P2). The TX leakage can be expressed as i_(P1)−i_(P2). The resistorsof the common mode sensing circuit sense the TX leakage as an electricalperformance characteristic of the duplexer. For instance, the voltage atthe center node of the resistors equalsVS−(R₁*2i_(R)+R₁*i_(P2)−R₂*i_(P1)), where VS is the voltage of thesecondary and 2i_(R) is the current from the received inbound RF signal.Assuming R₁=R₂ and i_(P1)=i_(P2), then the voltage at the center nodeequals ½ of VS. If, however, i_(P1) does not equal i_(P2), the voltageat the center node of the resistors will deviate from ½ VSproportionally to the difference. Note that the detector 820 outputs avoltage that is insensitive to a blocking signal being received by theantenna since the detector's inputs are coupled to the differentialinput of the LNA.

The detector 820 detects the difference of the voltage at the centernode of the resistors from ½ VS and provides an indication of thedifference to the processing module 822. The processing module 822,functioning as a tuning engine, interprets the difference and generatesa control signal to adjust the impedance of the balance network. Forexample, if i_(P1) is greater than i_(P2), then the common mode voltageof the sensing circuit (e.g., the center node of the resistors) will begreater than ½ VS, which indicates that the impedance of the balancenetwork 818 is too high. As such, the processing module 822 generates atuning signal 823 that reduces the impedance of the balance network 818.As another example, if i_(P1) is less than i_(P2), then the common modevoltage of the sensing circuit will be less than ½ VS, which indicatesthat the impedance of the balance network is too low. As such, theprocessing module 822 generates a tuning signal 823 that increases theimpedance of the balance network 818.

The processing module 822 may interpret the common mode voltagedeviation, determine a desired impedance for the balance network 818,and generate a tuning signal accordingly. Alternatively, the processingmodule 822 may iteratively generate tuning signals that adjust theimpedance of the balancing network 818 in steps until the desiredimpedance is achieved. With either approach, the processing module 822functions to keep the impedance of the balance network 818 substantiallymatching the impedance of the antenna (which varies over time, use,and/or environmental conditions) to minimize TX leakage.

FIG. 8 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM 960) and an SOC 962. The portion ofthe FEM 960 includes a power amplifier module (PA) 814, a duplexer 816,a balance network 818, and a sensing circuit 817. The duplexer 816includes a transformer (or other structure such as a frequency selectiveduplexer and/or an electrical balance duplexer). The sensing circuit 817includes a pair of resistors coupled across the secondary of thetransformer. The portion of the SOC 962 includes a peak detector 974, aprocessing module 976 (which performs the function of the tuningengine), and a single-ended low noise amplifier module (LNA 972).Alternatively, the peak detector 974 and/or the tuning engine may bewithin the FEM 960.

The circuits compensate for the TX leakage as discussed with referenceto FIG. 7. To further reduce common mode issues regarding processing theinbound wireless signal, the low noise amplifier 824 may be a singleended LNA. In this instance, one end of the secondary winding of theduplexer 816 is coupled to a common return and a second input of the lownoise amplifier is coupled to a voltage reference.

FIG. 9 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) 810 and an SOC 812. The front endmodule 810 includes a plurality of duplexer's 816-1 through 816-2 and aplurality of tunable balancing networks 818-1 through 818-2. Each of theduplexers 816 is coupled to an antenna 826-1 through 826-2. Thesystem-on-a-chip module 812 includes the processing module 822 and aplurality of detector modules 820-1 through 820-2.

Duplexer 816-1 isolates the first outbound wireless signal 835-1 from afirst inbound wireless signal 837-1. The first tunable balancing network818-1 is tuned via the processing module 822 and a first detector module820-1 as previously discussed. Similarly, duplexer 816-2 isolates asecond outbound wireless signal 835-2 from a second inbound wirelesssignal 837-2. The second tunable balancing network 818-2 is tuned via asecond tuning signal 823-2 by the processing module 822 and the seconddetection module 820-2.

In this embodiment, the first inbound and outbound wireless signals maybe transceived in a first frequency band and the second inbound andoutbound wireless signals may be transceived in a second frequency band.For example, each of the first and second frequency bands may bedifferent ones of the 900 MHz frequency band, the 1800 MHz frequencyband, the 1900 MHz frequency band, the 2 GHz frequency band, the 2.4 GHzfrequency band, the 5 GHz frequency band, the 60 GHz frequency band,etc.

FIG. 10 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) 810 and an SOC 812. A front end module830 includes a duplexer 838, a balance network, 842 and an antennatuning unit (ATU) 840. The system-on-a-chip module 832 includes a lownoise amplifier 852 and a processing module 846. The antenna tuning unit840 may include a cascading resister-capacitor-inductor circuit asshown. The duplexer 838 and the balance network 842 may includecomponents and function similarly to duplexers and balancing networksdiscussed throughout this detailed discussion.

In an example of operation, the antenna 834 receives an inbound wirelesssignal 837 from another communication device and transmits an outboundwireless signal 835. The inbound wireless signal 837 may be receivedfrom another wireless communication device in accordance with one ormore wireless communication protocols. The outbound wireless signal 835may be generated by a baseband processing, up conversion, and poweramplification in the front end module 830 and/or in the system-on-a-chipmodule 832.

To provide optimal antenna performance, the antenna tuning unit 840tunes an operational characteristic of the antenna (e.g., impedance,bandwidth, gain, quality factor, radiation pattern, polarization,efficiency, etc.) based on an antenna tuning signal. For example, theantenna tuning unit 840 adjusts a variable resistance and/or a variablecapacitance of the cascaded resistor-capacitor-inductor network inaccordance with the antenna tuning signal.

To produce the antenna tuning signal 841, the processing module 846generates a balance network tuning signal, which adjusts the balancingnetwork to substantially achieve a balanced impedance between theantenna and the balancing network. With the impedance of the antenna andbalancing network substantially matching, the processing module 846estimates the impedance, and/or other characteristics, of the antennabased on the inbound wireless signal 837, a test signal(s), and/orcomponents of the outbound wireless signal 835 received by the low noiseamplifier 852. For example, the antenna impedance may be estimated basedon known properties of the inbound and/or outbound wireless signals andproperties of the received inbound and/or outbound wireless signals. Asa specific example, if the impedance is lower than expected (e.g., 50Ohms), then the gain of the antenna is affected. By determining the gainaffects, the impedance can be estimated.

FIG. 11 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 830 and an SOC 832. The portion ofthe FEM 830 includes a power amplifier module (PA) 836, a duplexer 838,a balance network 842, an antenna tuning unit (ATU) 840, and a commonmode sensing circuit. The duplexer 838 includes a transformer (or otherstructure such as a frequency selective duplexer 838 and/or anelectrical balance duplexer 838) and the balancing network includes atleast a variable resistor and at least one variable capacitor. Thecommon mode sensing circuit includes a pair of resistors coupled acrossthe secondary of the transformer. The portion of the SOC 832 includes apeak detector 848, a tuning engine 850 (which may be implemented by theprocessing module 846), a look-up-table (LUT) 844, the processing module846, and a low noise amplifier module (LNA) 852. Alternatively, the peakdetector 848 and/or the tuning engine 850 may be within the FEM 830.

In addition to the functionality provided by the sensing circuit (i.e.,the resistors), the detector 848, the tuning engine 850, and the balancenetwork 842 to balance the impendence of the balance network 842 withthe impedance of the antenna; the FEM 830 includes the ATU 840. The ATU840 includes one or more fixed passive components and/or one or morevariable passive components. For example, the ATU 840 may include avariable capacitor-inductor circuit, a variable capacitor, a variableinductor, etc. As another example, the ATU 840 may include a tunableresistor-capacitor-inductor network and a tunable capacitor-inductornetwork. Another example of the ATU 840 is provided in FIG. 10.

In an example of operation, the PA 836 provides an amplified outbound RFsignal to the duplexer 838, which may include a transformer thatfunctions to isolate the outbound RF signal from an inbound RF signal.The duplexer 838 outputs the amplified outbound RF signal to the ATU840, which is tuned via settings stored in the LUT 844 to provide adesired antenna matching circuit (e.g., impedance, bandwidth, gain,quality factor, radiation pattern, frequency response, polarization,efficiency, etc.). To determine the setting to provide the ATU 840, theLUT 884 receives the antenna tuning signal 841 from the processingmodule 846. The LUT 884 then accesses an antenna setting 847 based onthe antenna tuning signal and provides it to the ATU. The ATU 840outputs the outbound RF signal to the antenna for transmission.

For an inbound RF signal, the antenna receives the signal and providesit to the ATU 840, which, in turn, provides it to the duplexer 838. Theduplexer 838 outputs the inbound RF signal to the LNA 852 and the commonmode sensing circuit. The common mode sensing circuit, the detector 848,the tuning engine 850, and the balance network 842 functions aspreviously described to balance the impedance of the balance network 842with the impedance of the antenna.

The processing module 846 is operable to monitor various parameters ofthe FEM 830. For instance, the processing module 846 may monitor theantenna impedance, the transmit power, the performance of the PA 836(e.g., gain, linearity, bandwidth, efficiency, noise, output dynamicrange, slew rate, rise rate, settling time, overshoot, stability factor,etc.), received signal strength, SNR, SIR, adjustments made by thetuning engine 850, etc. The processing module 846 interprets theparameters to determine if performance of the FEM 830 may be furtheroptimized. For example, the processing module 846 may determine that anadjustment to the ATU 840 will improve PA 836 performance. In this case,the processing module 846 addresses the LUT 844 to provide a desiredsetting to the ATU 840. If this change in the ATU 840 affects theimpedance balance between the ATU 840 and the balance network 842, thetuning engine 850 makes an appropriate adjustment.

In an alternate embodiment, the processing module 846 provides thefunctionality of the tuning engine 850 and balances adjustments to theATU 840 and to the balance network 842 to achieved a desired performanceof the FEM 830. In yet another alternate embodiment, the balance network842 is fixed and the ATU 840 provides the desired adjusts in the FEM 830to achieve impedance balance and to achieve the desired performance ofthe FEM 830.

FIG. 12 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 860 and an SOC 862. The front endmodule 860 includes a duplexer 870 and a gated balancing network 868.The system-on-a-chip module 862 includes a low noise amplifier 876 andan LNA by-pass circuit 875.

In an example of operation, the duplexer 870 provides electricalisolation between an outbound wireless signal 835 and an inboundwireless signal 837 that are transceived via the antenna 864. The gatedbalancing network 868 establishes an impedance that substantiallymatches an impedance of the antenna when the radio front end is in athird mode and establishes a low impedance with respect to the impedanceof the antenna when the radio front end is in one of a first and secondmodes. For example, the first mode corresponds to a receive mode of theradio front end when the inbound wireless signal is in accordance with atime division duplex (TDD) protocol; the second mode corresponds to atransmit mode of the radio front end when the outbound wireless signalis in accordance with the TDD protocol; and the third mode correspondsto the radio front end transceiving the inbound and outbound wirelesssignals is in accordance a frequency division duplex (FDD) protocol.

The LNA by-pass circuit 875 passes the inbound wireless signal to theLNA when the radio front end is in a first mode and bypasses the LNAwhen the radio front end is in a second mode. The low noise amplifier(LNA) 876 amplifies the inbound wireless signal to produce an amplifiedinbound wireless signal.

FIG. 13 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 860 and an SOC 862 for 2G and 3Gcellular telephone operations. The portion of the FEM 860 includes apower amplifier module (PA) 866, a duplexer 870, a gated balance network868, and a common mode sensing circuit (R1 and R2). The duplexer 870includes a transformer (or other structure such as a frequency selectiveduplexer and/or an electrical balance duplexer) and the gated balancingnetwork 868 includes a shorting switch, at least a variable resistor,and at least one variable capacitor. The portion of the SOC 862 includesa peak detector 872, a processing module 874, a switch (as the LNAby-pass circuit 875), and a low noise amplifier module (LNA 876).Alternatively, the peak detector 872 and/or the tuning engine 874 may bewithin the FEM 860.

In this embodiment, the duplexer is optimized for frequency divisionduplex (FDD), which is used in 3G cellular telephone applications. Inthis mode, the switch of the gated balancing network 868 and the switchof the LNA by-pass circuit are open such that the gated balancingnetwork provides an impedance substantially equal to the impedance ofthe antenna based on a tuning signal.

In time division duplex (TDD), which is used in 2G cellular telephoneapplications, the gated balancing network 860 is shorted via the switch.This essentially removes the 3-dB theoretical insertion loss limit andleaves just implementation loss. Note that for 2G transmissions, the LNAby-pass circuit switch is closed. For 2G receptions, the LNA by-passcircuit switch is open.

FIG. 14 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) 860 and an SOC 862 of FIG. 92 in 2G TXmode. In this mode, the LNA by-pass circuit switch shorts the LNA 876and the balance network switch shorts the balance network. With a shortacross the secondary winding, the primary windings are essentiallyshorted. Thus, the PA 866 is effectively directly coupled to theantenna.

FIG. 15 is a schematic block diagram of an embodiment of a portion ofeach of a front-end module (FEM) 860 and an SOC 862 of FIG. 92 in 2G RXmode. In this mode, the LNA switch is open and the balance networkswitch is closed, thus shorting the balance network. In thisconfiguration, the transformer is function as a transformer balun forthe receiver section.

FIG. 16 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 890 and an SOC 892. The portion ofthe FEM 890 includes a power amplifier module (PA) 896, a duplexer 898,a balance network 900, and a common mode sensing circuit (e.g., R1 &R2). The duplexer 898 includes a transformer (or other structure such asa frequency selective duplexer and/or an electrical balance duplexer)and the balancing network 900 includes at least a variable resistor andat least one variable capacitor and may further include an inductor. Theportion of the SOC includes a peak detector 902, a tuning engine 904(which may be implemented via a processing module), a detection 906module, and a low noise amplifier module (LNA) 908. Alternatively, thepeak detector 902, the leakage detection 906 module, and/or the tuningengine 904 may be within the FEM 890.

In an example of operation, the detection module detects a non-linearfunction of the power amplifier to produce a detected non-linearity. Forinstance, the detection module 906 detects variations of theon-resistance of the transistor within the PA 896 and/or within thebalance network 900. As a more specific example, as the PA 896 outputcurrent increases, the on-resistance of the transistors within the PA896 and/or within the balance network 900 increases. Such increasesaffect the overall impedance of the balance network 900. The detectionmodule 906 provides the detected non-linearity to the processing module904. Alternatively, or in addition to, the detection module 906 developsan envelope signal that tracks variations of the power amplifier basedon the non-linearity of the on-resistance and provide the envelopesignal to the processing module 904.

The detection module 906 further detects transmit leakage of theduplexer to produce detected transmit leakage. For example, thedetection module 906 receives a common mode signal from the sensingcircuit R1 and R2 and it generates the detected transmit leakagetherefrom. As previously mentioned, an imbalance in the duplexer willcause an offset in the common mode voltage, which is sensed by thesensing circuit.

The processing module generates a coarse tuning signal based on thedetected non-linearity and generates a fine tuning signal based on thedetected transmit leakage. The processing module provides the coarse andfine tuning signals to the tunable balancing network 900, establishes animpedance based on the coarse and fine tuning signals. As such, the dualfeedback loop of coarse and fine tuning adjusts for imbalances withinthe duplexer and performance variations (e.g., on-resistance) of thepower amplifier and/or balancing network 900.

FIG. 17 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 910 and an SOC module 912. Theportion of the FEM 910 includes a power amplifier module (PA) 916, aduplexer 918, a balance network 920, and a sensing circuit (e.g., R1 &R2). The duplexer 918 includes a transformer (or other structure such asa frequency selective duplexer 918 and/or an electrical balance duplexer918) and the balancing network includes at least a variable resistor andat least one variable capacitor. The portion of the SOC 912 includes apeak detector 922, a processing module 926 (which includes the functionof the tuning engine), and a low noise amplifier module (LNA) 924.Alternatively, the peak detector 922 and/or the tuning engine may bewithin the FEM 910.

In an example of operation, the processing module 926 generates a tuningsignal based on an imbalance in the duplexer and provides it to thebalancing network 920 as previously described. In addition, theprocessing module 926 determines a transmit power level of the outboundwireless signal, which may be done in a variety of ways. For example,the processing module may provide a transmit power levels signal to thepower amplifier 916, which it uses to establish the transmit powerlevel. As another example, the front end module 910 may include atransmit signal strength indicator, which provide the transmit powerlevel 928 to the processing module 926.

The processing module 926 compares the transmit power level 928 toisolation requirement. For example, when the transmit power level isrelatively low (e.g., is a smaller blocker for the inbound RF signaland/or the signal strength of the inbound RF signal is relatively high),the transmit leakage within the duplexer would be proportionally lower.In such instances, the amount of attenuation of the transmit signalwithin the duplexer may be reduced and still provide adequatecompensation of transmit leakage. As such, when the transmit power levelcompares favorably with an isolation requirement (e.g., is relativelylow), the processing module 926 generates an isolation adjustment signal921.

The processing module 926 sends the isolation adjustment signal 921 toat least one of the duplexer and the tunable balancing network. Uponreceiving the isolation adjustment signal, the duplexer 918 adjusts theelectrical isolation between the outbound wireless signal and theinbound wireless signal based on the isolation adjustment signal. Forexample, if the duplexer 918 is a frequency selective duplexer, itadjusts the electrical isolation between the outbound wireless signaland the inbound wireless signal by adjusting a filter of the one or morefilters. As another example, if the duplexer 918 is anelectrical-balance duplexer, the balancing network adjusts its impedancebased on the isolation adjustment signal as a trade-off between loadingof the duplexer 918 and the electrical isolation between the inbound andoutbound wireless signals.

FIG. 18 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 810 and an SOC module 812. The frontend module 810 includes a power amplifier, a duplexer 816, and a tunablebalancing network 818. The system-on-a-chip module 812 includes adetector module 820 and a processing module 822. The tunable balancingnetwork 818 includes a plurality of resistive elements 841-843, aplurality of capacitive elements 845-847, and a plurality of low voltageswitching elements 849-855. The tunable balancing network 818 mayfurther include one or more inductive elements 857 that are coupled to aresistive element and/or a capacitive element.

In an example of operation, the power amplifier amplifies anup-converted signal into an outbound wireless signal 835. The duplexer816 is operably coupled to an antenna and provides electrical isolationbetween the outbound wireless signal and an inbound wireless signal aspreviously discussed. The tunable balancing network establishes animpedance that substantially matches an impedance of the antenna basedon a tuning signal 823. For example, the tuning signal may activate(e.g., small scale or large scale) one or more of the low-voltageswitching elements of the tunable balancing network, which, in turn,couples one or more of the capacitive elements and one or more of theresistive elements to the duplexer as an impedance balancing load.Accordingly, by activating one or more of the low voltage switchingelements, the impedance of the balancing network 818 is tuned within agiven frequency range to substantially match that of the antenna. Notethat by using low voltage switching elements, the balancing network isreadily implementable on an integrated circuit where low-voltage is lessthan the voltage swing on the balancing network.

In the balancing network, a resistive element may be a resistor, atransistor-inductor based active resistor, and/or a switched capacitor.A capacitive element may be a capacitor and/or a varactor. Examples ofvarious resistive elements are shown in FIGS. 22 and 23.

FIG. 19 is a schematic block diagram of an embodiment of a small signalbalancing network 880 that includes a plurality of transistors,plurality of resistors, and a plurality of capacitors. The selection ofresistors to include in the balance network may be controlled by a firstset of bits of the tuning signal (e.g., 10 bits) and the selection ofcapacitors to include in the balance network may be controlled by asecond set of bits of the tuning signal (e.g., 5 bits).

In an example embodiment of the tunable balancing network, a firstresistive element of the resistive elements is coupled in series with afirst switching element of the low-voltage switching elements; a secondresistive element of the resistive elements is coupled in series with asecond switching element of the low-voltage switching elements. A commonnode of the second resistive element and the second switching element iscoupled to a control node of the first switching element. Such couplingcontinues for remaining ones of the plurality of resistive elements andlow-voltage switching elements.

Continuing with the example embodiment, a first capacitive element ofthe capacitive elements is coupled in series with a third switchingelement of the plurality of low-voltage switching elements and a secondcapacitive element of the capacitive elements is coupled in series witha fourth switching element of the low-voltage switching elements. Acommon node of the second capacitive element and the fourth switchingelement is coupled to a control node of the third switching element.Such coupling continues for remaining ones of the plurality ofcapacitive elements and low-voltage switching elements.

In this example, the impedance of the tunable balancing network is tunedin accordance with small-signaling of the tuning signal. For instance,as the voltage of the tuning signal 823 is adjusted (within a smallsignaling range such that the transistors are in a linear region), theon-resistance of the transistors is varies such that the series andparallel combination of on-resistance, resistors (r1-Rn) and capacitors(C1-Cn) provide the desired impedance for the balancing network.

FIG. 20 is a schematic block diagram of an embodiment of a large signalbalancing network 882 that includes an RLC (resistor-inductor-capacitor)network and a plurality of transistors. The transistors are gated on andoff to provide different combinations of resistors, inductors, and/orcapacitors of the RIC network to provide the desired impedance of thebalance network. In this instance, the transistors have a relativelysmall voltage swing, and thus lower voltage transistors can be used.

For example, if the balance network includes four resistor-transistorcircuits, four capacitor-transistor circuits, and one or more inductors,then the gating on & off the transistors establish the impedance for thebalancing network. For instance, each of the gates also is coupled toreceive a bit of a 4-bit control signal, where the gate of the leftouter-most resistor-transistor circuit receives the most significantbit, the gate of the next left most resistor-transistor circuit receivesthe next most significant bit, and so on. Further, the resistor of theleft most resistor-transistor circuit is R4, the resistor of the nextleft most resistor-transistor circuit is R3, and so on. Thus, for thisexample, when the 4-bit control signal is 0001, only the right mostresistor transistor circuit is on and its resistor, R1, provides theresulting resistance. When the 4-bit control signal is 0011, the tworight most resistor-transistor circuits are on and the resultingresistance is R1//R2. When the 4-bit control signal is 0111, the threeright most resistor-transistor circuits are on and the resultingresistance is R1//R2//R3. When the 4-bit control signal is 1111, allfour resistor-transistor circuits are on and the resulting resistance isR1//R2//R3//R4. The capacitor side of the balance network functions in asimilar manner.

As an alternative embodiment, each resistor-transistor circuit and eachcapacitor-transistor circuit may be independently controlled by a bit ofthe corresponding control signals. For a four resistor-transistorcircuit configuration as described in the preceding paragraph asmodified herein, a control signal of 1000 would yield a resistance ofR4; a control signal of 0100 would yield a resistance of R3; a controlsignal of 1010 would yield a resistance of R4//R2; and so on.

As yet another embodiment, a first resistive element of resistiveelements is coupled in series with a first switching element of theplurality of low-voltage switching elements; a second resistive elementof the resistive elements is coupled in series with a second switchingelement of the plurality of low-voltage switching elements; a firstcapacitive element of the capacitive elements is coupled in series witha third switching element of the low-voltage switching elements; and asecond capacitive element of the capacitive elements is coupled inseries with a fourth switching element of the low-voltage switchingelements.

In this embodiment, the impedance of the tunable balancing network istuned in accordance with large-signaling of the tuning signal. Forinstance, as the voltage of the tuning signal 823 is adjusted (within alarge signaling range such that the transistors are either “on” or“off:), the parallel and/or series combination of resistors (r1-Rn),capacitors (C1-Cn), and inductors (if any) provide the desired impedancefor the balancing network.

FIG. 21 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 1010 and an SOC module 1012. Theportion of the FEM 1010 includes a power amplifier module (PA) 1014, aduplexer 1016, a balance network 1018, and an antenna tuning unit (ATU)840. The duplexer 1016 includes a transformer (or other structure suchas a frequency selective duplexer 1016 and/or an electrical balanceduplexer 1016). The portion of the SOC 1012 includes a peak detector1002 (not shown), a processing module 1020 (which performs the functionof the tuning engine), and a low noise amplifier module (LNA) 1022.Alternatively, the peak detector 1002 and/or the tuning engine may bewithin the FEM 1010.

The balance network 1018 includes an RLC network having a plurality ofvariable resistors, a plurality of variable capacitors, and at least oneinductor as shown. In this embodiment, the balance network 1018 can betuned to provide a wide variety of impedance to enable a better matchingto the impedance of the antenna. In addition, the balancing network hasa wide tuning range for a desired voltage-standing-wave-ratio (VSWR)(e.g., 3:1), especially when tuned in conjunction with the tuning of theATU.

FIG. 22 is a schematic block diagram of an embodiment of an impedance ofa resistor-transistor (R-T) circuit of a balance network. The capacitorcorresponds to the parasitic capacitance of the transistor. Because theR-T circuit includes a real passive resistor, it contributes to the 3 dBtheoretical limit on insertion loss.

FIG. 23 is a schematic block diagram of another embodiment of animpedance of a resistor-transistor (R-T) circuit of the balance network.In this embodiment, the R-T circuit includes an inductively degeneratedcommon-source transistor. As such, it is an active resistance and doesnot contribute to the 3 dB theoretical limit on insertion loss. Thus,the only loss due to the balance network is implementation loss.

In particular, the R-T circuit provides an active gyrator within thebalancing network by using active devices instead of a passive resistor.With an active gyrator, the TX insertion loss does not change because itdepends on the value of the resistance, but the RX noise figure isimproved because the noise associated with the resistance is reduced inan active implementation. For example, in one possible implementation ofthe resistor as the input impedance of a common-gate MOSFET, theresistance is given by: R=1/gm. The noise power spectral density of suchresistor is 4KTγ/gm or 4KTγR where K is the Boltzmann's constant, T isthe temperature in Kelvin and γ is the thermal noise parameter and is afunction of the technology. On the other hand, a passive resistor has afixed noise power spectral density given by: 4KTR. For recent deepsubmicron technologies the value of γ is less than 1, thus a resistorimplemented using common-gate MOSFET generates less noise for the sameresistance.

FIG. 24 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 1010 and an SOC module 1012. Thefront end module 1010 includes the duplexer 816 and a balancing network1030. The system-on-a-chip module 812 includes the detector module 820and the processing module 822. The balancing network 1013 includes animpedance up converter 1032 and a baseband impedance circuit 1034.

In an example of operation, the baseband impedance circuit generates animpedance based on the tuning signal 823. The impedance up-converter1032, which is clocked at a desired frequency (e.g., f_(LO) or f_(RF)),up-converts the baseband impedance to a radio frequency impedance. Whentuned, the radio frequency impedance of the balancing network 1013substantially matches the impedance of the antenna 826 within a givenfrequency band of operation.

FIG. 25 is a schematic block diagram of an embodiment of the balancingnetwork 1030, which includes a plurality of transistors (e.g., amulti-phase transistor switching network as the up-conversion module)and a plurality of baseband impedances (Z_(BB)(s)) 396-402. Each of thebaseband impedances may include a plurality of capacitive elements, aplurality of resistive elements, and a plurality of switching elements.For each of the baseband impedances one or more of the capacitiveelements and/or one or more of the resistive are coupled together basedon the tuning signal to produce the baseband impedance. Note that aresistive element may be a resistor, a transistor-inductor based activeresistor, and/or a switched capacitor and that a capacitive element maybe a capacitor and/or a varactor.

In an example of operation, the balancing network receives the tuningsignal 832 and adjusts the baseband impedance accordingly. Thetransistors are switched using a four-phase clock as generated by aclock generator 404 of FIG. 26. As shown in FIG. 26, the clock generator404 produces four clocks signals each having a 25% duty cycle andsequentially offset by 90°. The clock signals have a frequencycorresponding to the carrier frequency of the inbound and/or outbound RFsignal and can be adjusted to better track the carrier frequency.

FIG. 27 illustrates the frequency translation of the baseband impedanceto the RF impedance. As shown, the baseband impedance is tuned to have adesired impedance at DC (e.g., 50 Ohms). The up-conversion modulemodulates the baseband impedance to +/−RF frequency.

FIG. 28 is a schematic block diagram of another embodiment of a balancenetwork that includes two impedance up-converters 1042, 1044 and twocorresponding baseband impedances (Zbb 1046, 1048). Each of theimpedance up-converters is clocked at a desired frequency (e.g., f_(RF)_(—) _(TX) and f_(RF) _(—) _(RX)). For example, up-converter 1042 may beclocked at a frequency within a first frequency band and up-converter1044 may be clocked at a frequency within a second frequency band.

As a further example, the first frequency band of operationcorresponding to a transmit frequency band of a wireless communicationprotocol and the second frequency band of operation corresponding to areceive frequency band of the wireless communication protocol. Asanother example, the first frequency band of operation corresponding toa frequency band of a first wireless communication protocol and thesecond frequency band of operation corresponding to a frequency band ofa second wireless communication protocol. Note that each of thecombinations of an impedance up-converter 1042, 1044 and itscorresponding baseband impedance may be implemented in a similar fashionas previously discussed with reference to FIG. 27.

FIG. 29 is a schematic block diagram of a front end module that includesa duplexer 816 and a balancing network 818. The duplexer 816 includes afirst winding 871, a second winding 773, a third winding 875, and acompensation module 877. The windings are coupled to have five nodes:the first node for operably coupling an antenna to the first winding;the second node operable to receive an outbound wireless signal andoperably couples the first winding to the second winding; the third nodeoperably couples the second winding to a balancing network; the fourthnode operably coupled to output a first signal component correspondingto an inbound wireless signal from the third winding; and the fifth nodeoperably coupled to output a second signal component corresponding to aninbound wireless signal from the third winding.

In an example of operation, the duplexer 816 receives an outboundwireless signal 835 at the common note between the first and secondwindings 871 & 873. The current of the outbound wireless signal 835 issplit between the first and second windings, which are represented asI_(TX-ANT) and I_(TX-BN). If the impedance of the balance network 818matches the impedance of antenna 826, then the transmit antenna currentand the balance network current will be approximately equal. With thesecurrents being approximately equal, they effectively cancel each otherwith respect to the third winding such that the third winding has anegligible TX leakage component. If, however, an imbalance existsbetween the impedance of the balance network 818 and the antenna 826, anon-negligible transmit leakage current will be present on the thirdwinding.

A series combination of the first winding 871 and second winding 873receives an inbound wireless signal, which has a current componentI_(RX), from the antenna 826. With a high output impedance of the PA,the series coupled first and second windings magnetically coupled thereceived current to the third winding 875 to produce the inboundwireless signal 837. If there is an imbalance between the impedances ofthe antenna 826 and a balance network 818, a transmit the leakagecurrent will be present on the third winding.

Even if the impedances of the balance network 818 and antenna 826 aresubstantially equal, there may be an imbalance within the duplexer thatcauses a transmit leakage current to appear on the third winding. Theimbalance may be caused by an imbalance between the parasiticcapacitances of the windings. In this instance, the compensation module877 is operable to compensate the electrical isolation between the firstand second signals and the outbound wireless signal due to an imbalancewithin the duplexer 816.

FIG. 30 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 930 and an SOC 932. The portion ofthe FEM 930 includes a power amplifier module (PA) 936, a duplexer 816,and a balance network 818. The duplexer 816 includes a transformerhaving three windings 871, 873, & 875, and parasitic capacitances Cp1 &Cp2. The compensation module 877 includes compensating capacitors Cc1 &Cc2. The portion of the SOC 932 includes a peak detector, a processingmodule (which includes the function of the tuning engine), and a lownoise amplifier module (LNA) 940. Only the LNA 940 is shown.

In this embodiment, the compensation capacitors Cc1 & Cc2 compensate formismatches of the parasitic capacitances (e.g., Cp1 and Cp2), which mayresult due to a mismatch between the windings of the primary (e.g., L1and L2). As such, the compensating capacitors (Cc1 and Cc2) are selectedsuch that Cp1+Cc1=Cp2+Cc2. By adding the compensation capacitors, theisolation bandwidth of the duplexer 938 is greater than without thecompensation capacitors and further reduces transmit leakage.

FIG. 31 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 930 and an SOC 932. The portion ofthe FEM 930 includes a power amplifier module (PA) 936, a duplexer 816,and a balance network 818. The duplexer 816 includes a transformerhaving three windings 871, 873, & 875, and parasitic capacitances Cp1 &Cp2. The compensation module 877 includes compensating capacitors Cc1 &Cc2, a detection module 891, and a processing module 893. The portion ofthe SOC 932 includes a peak detector, a processing module (whichincludes the function of the tuning engine), and a low noise amplifiermodule (LNA) 940. Note that the detection module 891 and/or theprocessing module 893 may be in the SOC 932.

In this embodiment, the compensation capacitors Cc1 & Cc2 are adjustableto compensate for mismatches of the parasitic capacitances (e.g., Cp1and Cp2). As such, the compensating capacitors (Cc1 and Cc2) areadjusted such that Cp1+Cc1=Cp2+Cc2. To determine the setting for thecompensating capacitors, the detection module detects an imbalancebetween the first and second parasitic capacitances. This may be done bydetecting a transmit leakage on the third winding, determining theportion of the transmit leakage to an imbalance between the impedancesof the balancing network and the antenna, and estimating (orcalculating) the portion of the transmit leakage due to parasiticcapacitance imbalance.

The processing module determines the capacitances of the first andsecond compensation capacitors based on the imbalance between the firstand second parasitic capacitances. The processing module then generatesa first capacitance setting based on the determined capacitance of thefirst compensation capacitor and a second capacitance setting based onthe determined capacitance of the second compensation capacitor.

FIG. 32 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 950 and an LNA 952. The portion ofthe FEM 950 includes the power amplifier module (PA) 954, the duplexer956, and the balance network 958. The duplexer 956 includes thetransformer having three windings and parasitic capacitance (Cp3 andCp4). The LNA 952 includes input transistors, which have parasiticcapacitance (Cp), bias transistors, a common-mode isolation circuit, andload impedances (Z). The common-mode isolation circuit includes aninductor (L3) as a common mode degeneration inductor and first andsecond capacitors. In an example, the first and second capacitors may bethe LNA's parasitic capacitors Cp3 & Cp4. In another example, the firstand second capacitors may be coupled in parallel with the parasiticcapacitors.

With the inclusion of the common-mode isolation compensation circuit inthe LNA 952, transmit leakage is further reduced. As such, even if thebalancing network and the compensation module cannot completelycompensated for the imbalances, the common mode isolation circuit of LNA952 further reduces the adverse affects of transmit leakage.

FIG. 33 is a schematic block diagram of an embodiment of an equivalentcircuit of a portion of each of a front-end module (FEM) and an LNA ofFIG. 32. This diagram illustrates how the common mode isolation isimproved. Imbalanced currents coupled to the secondary winding (L) bythe transformer's parasitic capacitance (Cp3 and Cp4), are coupled toseparate tank circuits formed by the inductor (L3) and the parasiticcapacitance of the input transistors. The tank circuits provide a highdifferential impedance, but a low common mode impedance, whichsuppresses the imbalances.

FIG. 34 is a schematic block diagram of an embodiment of a transformer980 of the duplexer. The transformer includes the primary windings (L1 &L2) and a secondary winding (L3). The primary windings each have thesame number of turns; the secondary winding may have the same number ofturns as a primary winding or different number of turns. The orientationof the windings is as shown.

FIG. 35 is a diagram of an example of an implementation of a transformerimplemented on 4 thick metal layers of an integrated circuit, of an ICpackaging substrate, and/or on a printed circuit board. The primarywindings are on the top two layers and the secondary winding is on thetwo lower layers. The windings of the secondary, which are on the thirdand fourth layers, may be connected in series or in parallel.

FIG. 36 is a diagram of another example of an implementation of atransformer on 3 thick metal layers of an IC, of an IC packagesubstrate, and/or of a printed circuit board. The primary windings areon the top layer and use the next layer for interconnections and may berotated by 90° with respect to the orientation of the secondary winding.The secondary winding is on the second and/or third lower layers.

FIG. 37 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 990 and an LNA 992. The front-endmodule 990 includes a power amplifier 994, a duplexer 996, a balancenetwork 1000, and a tone injection module 998. The system-on-a-chipmodule 992 includes a processing module 1004 and may further includeother components as previously described.

In situations where the transmit noise in the receive path and/orreceive band noise is below the noise floor of the low noise amplifier,further compensation of the transmit noise and/or receive band noise canbe detected and subsequently compensated for by including a toneinjection module 998. For example, the tone injection module 998 (whichmay be an oscillator, a phase locked loop, a direct digital frequencysynthesizer, etc.) produces, in a first mode, a tone 995 having acarrier frequency that is substantially similar to a carrier frequencyof an inbound wireless signal. The tone 995 is injected into theoutbound wireless signal received by the duplexer 996, which may be doneby summing the tone with the output of the PA or with the input of thePA.

The duplexer 996, which operably coupled to an antenna, provides, in thefirst mode, electrical isolation between the outbound wireless signaland a combination signal of the tone and inbound wireless signal. In asecond mode, the duplexer 996 provides electrical isolation between theoutbound wireless signal and the inbound wireless signal (e.g., the toneis not present). The balancing network 1000 establishes an impedancethat substantially matches an impedance of the antenna based on a tuningsignal 997.

The processing module 1004 determines an amplitude of a tone componentof the combination signal. This may be done at baseband, an intermediatefrequency, or at RF. The processing module 1004 then correlates theamplitude of the tone component to an inbound frequency band isolationsignal (e.g., a measure of the receive band noise and/or the transmitnoise on the receive path). The processing module 1004 then adjustsbaseband processing of a down converted representation of thecombination signal based on the inbound frequency band isolation. Forexample, with the inbound frequency band isolation signal being ameasure of receive band noise and/or transmit noise on the receive path,these noise components can be digitally filtered during the basebandconversion process.

The processing module 1004 may be further operable to enable the firstmode when noise of the inbound wireless signal compares favorably to anoise threshold (e.g., is below the noise floor of the LNA).Alternatively, the processing module enables the second mode when thenoise of the inbound wireless signal compares unfavorably to the noisethreshold, wherein the tone injection module is disabled in the secondmode.

The processing module 1004 may still be further operable to generate atuning signal 997 based on electrical performance characteristic ofduplexer 996 as previously discussed. The processing module then sendsthe tuning signal 997 to the balancing network 1000, which adjusts theimpedance based on the tuning signal 997. The processing module thenadjusts the tuning signal based on inbound frequency band isolation tofurther compensate noise on the receive path.

FIG. 38 is a schematic block diagram of another embodiment of a portionof each of a front-end module (FEM) 990 and an SOC 992. The portion ofthe FEM 990 includes a power amplifier module (PA) 994, a duplexer 996,a balance network 1000, a tone injection module 998, and a sensingcircuit (e.g., R1 & R2). The duplexer 996 includes a transformer (orother structure such as a frequency selective duplexer and/or anelectrical balance duplexer) and the balancing network 1000 includes atleast a variable resistor and at least one variable capacitor. Theportion of the SOC 992 includes a detector 1002, a processing module1004 (which performs the function of the tuning engine), a basebandprocessing unit 1008, and a low noise amplifier module (LNA) 1006.Alternatively, the peak detector 1002 and/or the tuning engine may bewithin the FEM 990.

In an example of operation, the sensing circuit, the tuning engine, thedetector 1002 and the balance network 1000 function as previouslydiscussed to balance the impedances of the balancing network and theantenna. In many instances, this will reduce the transmitter (TX) and/orreceiver (RX) noise in the receiver band below or comparable to thenoise floor of the LNA 1006. With the TX and/or RX noise at or below thenoise floor, it is difficult to track, which adversely affects thetracking of the impedance of the antenna.

To improve the tracking of the antenna impedance, the tone injection 998module injects a tone in the receiver frequency band (e.g., A cos(ω_(RX)_(—) _(RF)(t)). The duplexer 996 attenuates the RX tone differently thana TX signal because it is in the RX band and the duplexer 996 andbalance network 1000 are tuned for the TX band. As such, a readilydetectable leakage signal is produced on the RX side of the duplexer 996(e.g., on the secondary of the transformer).

The RX tone-based leakage signal is propagated through the receiversection until it is converted into a baseband signal. At baseband, thetone amplitude is a measure of the RX band isolation. From the measureof RX band isolation, the antenna's impedance can be determined. As theantenna impedance changes, the antenna tuning unit and/or the balancenetwork 1000 may be adjusted to track the antenna's impedance. Note thatthe tone may be easily removed at baseband.

In an example of operation, the power amplifier amplifies anup-converted signal to produce an outbound wireless signal. The toneinjection module produce a tone having a carrier frequency that issubstantially similar to a carrier frequency of an inbound wirelesssignal, where the tone signal is combined with the outbound wirelesssignal. The duplexer 996 provides electrical isolation between theoutbound wireless signal and a combination signal of the tone and theinbound wireless signal. The balancing network establishes an impedancethat substantially matches an impedance of the antenna based on a tuningsignal.

The duplexer 996 provides an inbound wireless signal to the low noiseamplifier 1006, where the inbound wireless signal includes an inbound RFsignal component and a tone component. The LNA amplifies the combinationsignal to produce an amplified combination signal, which is convertedinto a baseband or near-baseband signal by the down conversion module1007.

The processing module generates the tuning signal based on an electricalperformance characteristic of the duplexer as previously discussed. Theprocessing module then converts the baseband or near-baseband signalinto a baseband tone signal and a baseband inbound signal. Theprocessing module then determines an inbound frequency band isolationbased on the baseband tone signal (which is a measure of RX bandisolation) and adjusts the tuning signal based on the inbound frequencyband isolation. The processing module may also adjust the basebandinbound signal based on the inbound frequency band isolation tocompensate for transmit noise in an inbound frequency band.

In the preceding figures, some elements have common or similar names andthe same or different reference numbers. For these elements (e.g., theFEM, the SOC, the duplexer, the balancing network, etc.), an element mayinclude any combination of features and/or characteristics of theelements having the various names and/or different reference numbers.

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “operably coupled to”, “coupled to”, and/or “coupling” includesdirect coupling between items and/or indirect coupling between items viaan intervening item (e.g., an item includes, but is not limited to, acomponent, an element, a circuit, and/or a module) where, for indirectcoupling, the intervening item does not modify the information of asignal but may adjust its current level, voltage level, and/or powerlevel. As may further be used herein, inferred coupling (i.e., where oneelement is coupled to another element by inference) includes direct andindirect coupling between two items in the same manner as “coupled to”.As may even further be used herein, the term “operable to” or “operablycoupled to” indicates that an item includes one or more of powerconnections, input(s), output(s), etc., to perform, when activated, oneor more its corresponding functions and may further include inferredcoupling to one or more other items. As may still further be usedherein, the term “associated with”, includes direct and/or indirectcoupling of separate items and/or one item being embedded within anotheritem. As may be used herein, the term “compares favorably”, indicatesthat a comparison between two or more items, signals, etc., provides adesired relationship. For example, when the desired relationship is thatsignal 1 has a greater magnitude than signal 2, a favorable comparisonmay be achieved when the magnitude of signal 1 is greater than that ofsignal 2 or when the magnitude of signal 2 is less than that of signal1.

While the transistors in the above described figure(s) is/are shown asfield effect transistors (FETs), as one of ordinary skill in the artwill appreciate, the transistors may be implemented using any type oftransistor structure including, but not limited to, bipolar, metal oxidesemiconductor field effect transistors (MOSFET), N-well transistors,P-well transistors, enhancement mode, depletion mode, and zero voltagethreshold (VT) transistors.

The present invention has also been described above with the aid ofmethod steps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention.

The present invention has been described, at least in part, in terms ofone or more embodiments. An embodiment of the present invention is usedherein to illustrate the present invention, an aspect thereof, a featurethereof, a concept thereof, and/or an example thereof. A physicalembodiment of an apparatus, an article of manufacture, a machine, and/orof a process that embodies the present invention may include one or moreof the aspects, features, concepts, examples, etc. described withreference to one or more of the embodiments discussed herein.

The present invention has been described above with the aid offunctional building blocks illustrating the performance of certainsignificant functions. The boundaries of these functional buildingblocks have been arbitrarily defined for convenience of description.Alternate boundaries could be defined as long as the certain significantfunctions are appropriately performed. Similarly, flow diagram blocksmay also have been arbitrarily defined herein to illustrate certainsignificant functionality. To the extent used, the flow diagram blockboundaries and sequence could have been defined otherwise and stillperform the certain significant functionality. Such alternatedefinitions of both functional building blocks and flow diagram blocksand sequences are thus within the scope and spirit of the claimedinvention. One of average skill in the art will also recognize that thefunctional building blocks, and other illustrative blocks, modules andcomponents herein, can be implemented as illustrated or by discretecomponents, application specific integrated circuits, processorsexecuting appropriate software and the like or any combination thereof.

1. A radio front module comprises: a power amplifier operably coupled toamplify an up-converted signal into an outbound wireless signal; aduplexer operably coupled to an antenna and operable to provideelectrical isolation between the outbound wireless signal and an inboundwireless signal; and a tunable balancing network operably coupled to theduplexer and operable to establish an impedance that substantiallymatches an impedance of the antenna, wherein the tunable balancingnetwork includes: a plurality of capacitive elements; a plurality ofresistive elements; and a plurality of low-voltage switching elementsoperable to, and in accordance with a tuning signal, couple one or moreof the plurality of capacitive elements and one or more of the pluralityof resistive elements to the duplexer as an impedance balancing load. 2.The radio front module of claim 1, wherein the tunable balancing networkfurther comprises: a first resistive element of the plurality ofresistive elements coupled in series with a first switching element ofthe plurality of low-voltage switching elements; a second resistiveelement of the plurality of resistive elements coupled in series with asecond switching element of the plurality of low-voltage switchingelements, wherein a common node of the second resistive element and thesecond switching element is coupled to a control node of the firstswitching element; a first capacitive element of the plurality ofcapacitive elements coupled in series with a third switching element ofthe plurality of low-voltage switching elements; and a second capacitiveelement of the plurality of capacitive elements coupled in series with afourth switching element of the plurality of low-voltage switchingelements, wherein a common node of the second capacitive element and thefourth switching element is coupled to a control node of the thirdswitching element, wherein impedance of the tunable balancing network istuned in accordance with small-signaling of the tuning signal.
 3. Theradio front module of claim 1, wherein the tunable balancing networkcomprises: a first resistive element of the plurality of resistiveelements coupled in series with a first switching element of theplurality of low-voltage switching elements; a second resistive elementof the plurality of resistive elements coupled in series with a secondswitching element of the plurality of low-voltage switching elements; afirst capacitive element of the plurality of capacitive elements coupledin series with a third switching element of the plurality of low-voltageswitching elements; and a second capacitive element of the plurality ofcapacitive elements coupled in series with a fourth switching element ofthe plurality of low-voltage switching elements, wherein impedance ofthe tunable balancing network is tuned in accordance withlarge-signaling of the tuning signal.
 4. The radio front module of claim1, wherein the tunable balance network further comprises: one or moreinductive elements operably coupled to at least: one of the resistiveelements of the plurality resistive elements; and one of the capacitiveelements of the plurality of capacitive elements.
 5. The radio frontmodule of claim 1, wherein a resistive element of the plurality ofresistive elements comprises one or more of: a resistor; atransistor-inductor based active resistor; and a switched capacitor. 6.The radio front module of claim 1, wherein a capacitive element of theplurality of capacitive elements comprises one or more of: a capacitor;and a varactor.
 7. The radio front module of claim 1 further comprises:an antenna tuning unit operably coupled between the duplexer and theantenna, wherein the antenna tuning unit tunes an operationalcharacteristic of the antenna based on an antenna tuning signal; and thetunable balancing network including: a first set of the plurality ofcapacitive elements having a first capacitive common node; a second setof the plurality of capacitive elements having a second capacitivecommon node; a first set of the plurality of resistive elements having afirst resistive common node; a second set of the plurality of resistiveelements having a second resistive common node; and an inductor coupled,at one end, to the first capacitive and resistive common nodes andcoupled, at another end, to the second capacitive and resistive commonnodes such that the tunable balancing network has a wide tuning rangefor a desired voltage-standing-wave-ratio (VSWR).
 8. A radio frontmodule comprises: a power amplifier operably coupled to amplify anup-converted signal into an outbound wireless signal; a duplexeroperably coupled to an antenna and operable to provide electricalisolation between the outbound wireless signal and an inbound wirelesssignal; and a tunable balancing network operably coupled to theduplexer, wherein the tunable balancing network includes: a basebandimpedance circuit; and an impedance up-conversion module operablycoupled to up-convert a baseband impedance of the baseband impedancecircuit to produce a radio frequency (RF) impedance that substantiallymatches an impedance of the antenna in a frequency band of operation. 9.The front end module of claim 8, wherein the baseband impedance circuitcomprises: a plurality of capacitive elements; a plurality of resistiveelements; and a plurality of switching elements operable to, and inaccordance with a tuning signal, couple one or more of the pluralitycapacitive elements and one or more of the plurality of resistiveelements to produce the baseband impedance.
 10. The radio front moduleof claim 9, wherein a resistive element of the plurality of resistiveelements comprises one or more of: a resistor; a transistor-inductorbased active resistor; and a switched capacitor.
 11. The radio frontmodule of claim 9, wherein a capacitive element of the plurality ofcapacitive elements comprises one or more of: a capacitor; and avaractor.
 12. The front end module of claim 8, wherein the impedanceup-conversion module comprises: a multi-phase transistor switchingnetwork operably coupled to receive a multi-phase clock signal toup-convert the baseband impedance into the RF impedance.
 13. The frontend module of claim 8, wherein the tunable balancing network furthercomprises: a second baseband impedance circuit; and a second impedanceup-conversion module operably coupled to up-convert a second basebandimpedance of the second baseband impedance circuit to produce a secondRF impedance that substantially matches an impedance of the antenna in asecond frequency band of operation.
 14. The front end module of claim 13further comprises: the frequency band of operation corresponding to atransmit frequency band of a wireless communication protocol; and thesecond frequency band of operation corresponding to a receive frequencyband of the wireless communication protocol.
 15. The front end module ofclaim 8 further comprises: the frequency band of operation correspondingto a frequency band of a first wireless communication protocol; and thesecond frequency band of operation corresponding to a frequency band ofa second wireless communication protocol.